The present invention is concerned with enol ether derivatives of oxicams (1,1-dioxides of N-heteroaryl-4-hydroxy-2-methyl-2H-1,2-benzothiazine-3-carboxamides and N-heteroaryl-4-hydroxy-2-methyl-2H-thieno[2,3-e]-1,2-thiazine-3-carboxamid es). These ethers are valuable as so-called prodrugs of these nonsteroidal antiinflammatory agents, known generically as oxicams.
The oxicams (including enol esters) and their utility as antiinflammatory agents are disclosed in U.S. Pat. Nos. 3,591,584; 3,787,324; 3,822,258; 4,180,662; and 4,309,427; Belgian Pat. No. 895,712; and European patent application No. 85,866. Prior described enol ethers of oxicams (U.S. Pat. No. 3,892,740) do not exhibit present antiinflammatory activity.